This invention relates to a combustion apparatus such as a fireplace, and, in particular, to a fireplace having a circulation passageway within the fireplace through which room air passes and is heated prior to being exhausted at a higher temperature to the room being heated.
Known in the art are a multitude of different types of combustion apparatus, including fireplaces such as freestanding models and zero clearance models. These fireplaces commonly include housings or shells that surround the combustion chambers or fireboxes where combustion of fuel occurs. The walls of the housing are typically constructed in spaced relationship with some or all of the walls of the combustion chamber, including the bottom wall and top wall which form the floor and ceiling of the combustion chamber. The resulting space or plenums provided between the combustion chamber and housing permits the formation of passageways suitable to circulate air. Existing fireplaces have used these passageways to circulate air to serve a number of nonexclusive purposes, including the transfer of heat to room air which is inlet into these passageways. The inlet room air is discharged from the fireplace at a higher temperature to heat the room in which the fireplace unit is installed.
The forward, bottom portion of the combustion chamber often becomes very hot during fireplace operation and therefore serves as a valuable source of heat to be transferred to circulating room air. To utilize this heat, many conventional fireplaces use a C-shaped room air circulation passageway which extends around the bottom, rear, and top of the combustion chamber. One shortcoming with this design results from the way room air reaches these passageways. Apertured or louvered grills disposed along the bottom and top portions of the front wall of the fireplace and in communication with the circulation passageway respectively serve as inlets and outlets for the room air being heated. These plainly visible louvers are generally unsightly and detract from the overall appearance of the fireplace. Moreover, the presence of these louvers prevents the front of the fireplace around the opening to the combustion chamber from being covered with an aesthetically pleasing brick or marble facade. Another disadvantage to such these passageways is the potential expense of this ductwork extending completely around the fireplace.
Fireplaces attempting to reduce the unsightliness of a louvered fireplace face have met with limited success. For example, one existing fireplace utilizes a heat exchanger below the fireplace floor into which room air inlets and outlets through a slot disposed in the front face of the fireplace adjacent to the floor of the room. A circulating fan draws room air through a portion of the slot, circulates this introduced room air below the combustion chamber to be warmed, and then exhausts the now heated room air back to the room through different portions of the slot. Because this room air inlet/outlet slot is spaced below the opening into the combustion chamber, it may be more visible to a casual observer. In addition, this positioning of the slot prevents a slab of marble, for example, from covering the entire fireplace face between the room floor and the combustion chamber opening, as such marble facing would block the slot. Still another shortcoming of this fireplace is that an access panel allowing access to the fan within the heat exchanger is positioned in the front face of the fireplace and detracts from a desired continuous fireplace face.
Additional heat exchangers which attempt to capitalize upon the available heat at the bottom, forward portion of the fireplace combustion chamber are disclosed in U.S. Pat. Nos. 4,085,727 and 4,154,214. These designs are undesirable from an aesthetics standpoint as they respectively utilize a louvered front panel and an external blower. Still other heat exchangers, such as those disclosed in U.S. Pat. Nos. 4,512,329 and 5,000,162, utilize ducts for circulating room air which may be visibly positioned on top of the fireplace hearth and which thereby detract from the overall aesthetics of the fireplace.
Thus, it is desirable to provide a fireplace which has a clean face while providing inlets and outlets to a room air circulating passageway used as a heat exchanger within the fireplace. It is further desirable to provide a fireplace which allows access to blowers within a heat exchanger below the combustion chamber without detracting from the overall appearance of the fireplace face.